Peel and wash 1 carrot. Peel the onion and lard with cloves. Boil the carrot, onion and peppercorns in a large pot with 2 litres of water, 1/8 litre of vinegar, white wine, lemon juice, 1 teaspoon of salt and 1 teaspoon of sugar. Carefully wash the carp under cold water and season inside with salt and a little pepper. Place an inverted cup in the carp belly so that the carp can be placed on a plate. Bring 1/8 litre vinegar to the boil in a small pot and pour it evenly over the carp until it is blue.
Place the carp carefully on the fat pan of the oven. Add vegetable stock. Put the fat pan into the preheated oven (electric cooker: 150 °C/ circulating air: 125 °C/ gas: level 1) and cook for 20-25 minutes. Peel and wash the potatoes. Bring the stock to the boil. Cook the potatoes for about 20 minutes. Peel remaining carrots, clean leek and wash both, cut into thin strips and cook in a little salted water for about 5 minutes. Whip cream until stiff. Mix with horseradish. Season to taste with sugar, salt and pepper. Carefully remove the carp from the stock, drain and place on a preheated plate. Arrange vegetables and bouillon potatoes around the carp.
Peel remaining carrots, clean leek and wash both, cut into thin strips and cook in a little salted water for about 5 minutes. Whip cream until stiff. Mix with horseradish. Season to taste with sugar, salt and pepper. Carefully remove the carp from the stock, drain and place on a preheated plate. Arrange vegetables and bouillon potatoes around the carp. Garnish with parsley. Add horseradish cream and liquid hot butter to taste